Developing functional nanocellulose-based materials while well maintaining their inherent excellent attributes is crucial to achieve the value-added applications. However, their inherent flammability largely limits their potential applications in many fields with fire-safety concerns. In this work, an intrinsically flame-retardant nanofibrillated cellulose (NFC) was successfully prepared from kraft and unbleached bamboo pulps, respectively, via a three-step strategy involving quaternized pre-treatment, mechanical disintegration and subsequent borylation. TEM images show that the well-defibrillated cellulose nanofibrils with an average diameter of 5–9 nm were successfully obtained. The morphological, physicochemical, mechanical, thermal and flame-retardant characteristics of NFC suspensions, and their resulting films were systematically characterized. The borylated NFC film from the kraft pulp (B/Q-NFC) exhibits remarkably improved char yield while retaining high degree of fibrillation, optical transparency and mechanical properties of the Q-NFC one. Despite relatively lower optical transmittance and tensile strength, the lignin-containing NFC (L-Q-NFC) from unbleached pulp exhibits better thermal stability and outstanding UV-shielding function. Flame-retardant properties of borylated NFC samples were comprehensively investigated in terms of microscale combustion calorimetry (MCC), limiting oxygen index (LOI), vertical burning, and cone calorimetry tests. A synergistic effect was noted between B and lignin species in promoting flame resistance of Q-NFC matrix (L-B/Q-NFC). When being used as flame-retardant coatings on the filter paper and PET film, both of borylated NFC films display excellent flame-retardancy and smoke-suppression effects. In combination with of surface and bulk chemical composition analysis, TGA results as well as oxygen-permeability and thermal diffusivity measurements, the flame-retardant mechanism of borylated NFC films was elucidated. These favorite features enable them to act as sustainable fire-protective coatings for many fields such as thermal insulation, electronics, separators for lithium-ion battery, etc.

开发功能性纳米纤维素基材料，同时保持其固有的优异特性，对于实现增值应用至关重要。但是，它们固有的易燃性极大地限制了它们在许多涉及消防安全的领域中的潜在应用。在这项工作中，通过季铵化预处理，机械崩解和随后的硼化三步策略，分别从牛皮纸浆和未漂白的竹浆中成功制备了固有阻燃纳米原纤化纤维素（NFC）。TEM图像显示，成功获得了平均直径为5–9 nm的除纤颤纤维素纳米原纤维。NFC悬浮液的形态，物理化学，机械，热学和阻燃特性，对他们拍摄的电影进行了系统地表征。牛皮纸浆（B / Q-NFC）中的硼化NFC膜具有显着提高的炭收率，同时保留了Q-NFC的高原纤化度，光学透明性和机械性能。尽管光学透射率和拉伸强度相对较低，但未漂白纸浆中含木质素的NFC（LQ-NFC）仍具有更好的热稳定性和出色的紫外线防护功能。在微尺度燃烧量热法（MCC），极限氧指数（LOI），垂直燃烧和锥形量热法测试方面，对硼化NFC样品的阻燃性能进行了全面研究。注意到B和木质素物种之间在促进Q-NFC基质（LB / Q-NFC）的阻燃性方面具有协同作用。当用作滤纸和PET膜上的阻燃涂料时，两种硼化的NFC膜均具有出色的阻燃性和抑烟效果。结合表面和本体化学成分分析，TGA结果以及氧渗透率和热扩散率测量，阐明了硼化的NFC薄膜的阻燃机理。这些最喜欢的功能使它们能够在许多领域用作可持续的防火涂料，例如隔热，电子，锂离子电池隔膜等。阐明了硼化NFC薄膜的阻燃机理。这些最喜欢的功能使它们能够在许多领域用作可持续的防火涂料，例如隔热，电子，锂离子电池隔膜等。阐明了硼化NFC薄膜的阻燃机理。这些最喜欢的功能使它们能够在许多领域用作可持续的防火涂料，例如隔热，电子，锂离子电池隔膜等。